Pressure exerting mechanism



,March .1945 v. E. ROSENLUND ET AL 2,371,547

PRESSURE EXERTING MECHANISM Filed Feb. 1, 1945 2 Sheets-Sheet 1 INVENTOR I Icfor EJibsenZund I BY C'Zarence Sfilzak ATTORNEY v. E. ROSENLUND ETAL PRESSURE EXERTING MECHANISM March 13, 1945.

Filed Feb. 1 1943 BY (Yarence .55 Fza/r 2 Sheets-Sheet 2 INVENTOR l tciarE Fawn ATTOR.N\EY

lurzcl Patented Mar. 13, 1 945 PRESSURE EXERTING MECHANISM Victor E. Rosenlund, Paxton, and. Clarence S.

Fuzak, Worcester, Mass., assignors to Reed- Prentice Corporation, Worcester, Mass., a corporation of Massachusetts Application February 1, 1943, Serial No. 474,382

Claims.

The present invention relates to an improved mechanism for exerting and sustaining pressure between two relatively movable members, such as the dies or molds of a pressure casting machine, or any other machine requiring the development of heavy and sustained pressure between members relatively movable with relation to each other for the performance of a pressing operation.

Pressure exerting mechanisms of this general character, as heretofore constructed, have usually employed operating linkages, working on-the tog,-

gle principle for actuating the movable members of the mechanisms. It has been found that the development ofheavy pressures imposes severe strains on the pivots and connecting elements of such linkages, with resulting breakages of the linkage parts and wear-in the pivots, unless the entire mechanism is of very heavy construction.

According to the present invention, there is provided an improved pressure exerting mechanism, characterized by the provision of elements for actuating the movable members that operate with a sliding action during the major portion of the travel of the latter, without the developmentof pressure, followed by shifting of these actuating elements into pressure exerting position as the relatively movable members come into contact. Such shifting of the actuating elements is accompanied by their wedging engagement with selfalining abutments mounted on a fixed member, so that heavy pressure is developed and maintained between the relatively movable members with the expenditure of a minimum amount ofpower. This same self-alining action of the abutments also permits ready release of the actuating elements preparatory to separation of the pressureexerting members.

The above and other advantageous features of Fig. 4 is a view'similar to Fig. 3, showing the parts in pressure exerting position.

Fig. 5 is a fragmentary sectional view along the line 5--5 of Fig. 2, looking in the direction of the arrows.

Fig. 6 is a vertical sectional view along the line 8-6 of Fig. 1.

Fig. 7 is a vertical sectional view along the line 'l-l of Fig. 1.

Referring to the drawings, the machine consists of a frame I, providing parallel spaced side members 2 connected by an end member 3 on which a fixed die plate 4 is mounted. A second die plate 5 is slidably mounted for movement on the frame through its cooperation with horizontal ways 6 provided by the side members 2. The die plate 5 is thus guided for movement on the frame, so that the surface thereof is maintained in substantially parallel relation with respect to the opposed surface of the fixed die plate 4, and suitable dies, indicated in dotted lines at D, are adapted to be mounted on the plates 4 and 5.

The plate 5 is movable on the ways'fi by means of actuating elements 1, each pivotally connected to the plate 5 at one end by a pin 8, and'at its other end to links 9 by a pin l0. The-inner ends of the links 9 are connected to a cross head II by pins 9a, with the cross head it being movable on rods l2 extending between the plate 5 and a. yoke l3 adjustably mounted within the frame I,

as will be later described.

The yoke It provides a cylinder I4, and a piston l5 movable within the cylinder It, provides a rod it connected at its end to the cross head II. The piston I5 is adapted to be moved back and forth within the cylinder it through control of the admission of a fluid pressure medium, and when the piston I5 is in the left-hand end of the cylinderas shown in Fig. 11 the actuating elements I are maintained in substantially parallel relation within the yoke l3, with the dies D open. When the piston I5 is moved to the right for the die closing operation; the cross head ll moves the elements I directly, with flat surfaces I! on the elements bearing on parallel ways l8 provided on the inside of the yoke l3. As the die on the movableplate 5 nears engagement with the die on the fixed plate 4, the elements I reach the ends of the ways l8 and are then free to swing outwardly with respect to wedging abutments I9 turn about its longitudinal axis X-X. That portion of the abutment II which extends beyond the seat, provides a flat surface 26 that is adapted to cooperate with a corresponding fiat surface 23 provided by a shoe: 21 of hardened metal carried at the free end of an element 1.

When the elements 1 are in their retracted position within the yoke, with the dies separated, it is to be noted that each abutment i9 is maintained in the position of 'Fig. 3 by a spring 28 connected to each end of the abutment, with the ends of the springs 28 being anchored in lugs 23 provided by the yoke l3. Since the central axis of each spring 28 passes through the pivotal axis of the abutment l9, each abutment is yieldingly maintained inthe position of Fig. 3

at an angle to the ways 48 on which the elements I slide at the start of the die closing movement.

It is to be noted that the end surface 26 of each shoe 21 at the end of an element 1 has an inclination with respect to the guide surface 11, subs'tantially equal to the normal angle of an abut-.

ment surface '25. Consequently, as the elements 1 reach-the ends of the ways I8, the surfaces 25 and 26 slide into engagement, as indicated in dotted lines in Fig, 4. Since at this point the dies are closed (or substantially so), continued movement of the cross head H to the full line position of Fig. 4, will result in a wedging action tending to compress the elements 1 longitudinally, and through them exert a heavy closing pressure on the dies which will be maintained as long as pressure is maintained on the piston l5. As the elements 1 reach their extended position, the abutments iii are free to turn axially in their seats 2|, while at the same time they are rigidly backed up by the blocks 22. The net result is a self-aiming action of each abutment I9 so that the angle of its surface 25 always corresponds with the angle of the cooperating surface 26 on an element 1 during the entire time that these surfaces are in engagement. Therefore, the transmission and maintenance of extremely heavy pressures through the elements 1 is obtained without appreciable wear of the hardened surfaces 25 and 26,. such as would occur were the abutments entirely rigid and incapable of turning on their axes. The above noted selfj'-alinement of the cooperating surfaces of the abutments l9 and actuating elements 1 prevents any jamming of the parts, such as would prevent ready opening of the dies after sustaining heavy pressure during the molding operation. That is to say, when the cross head ll starts its dieeopening movement, the slightest change in the" angles of the surfaces 26 as the elements start to move inwardly, will be accompanied by corresponding change in the angles of the cooperating abutment surfaces 25. Therefore, the elements 1 will readily withdraw from engagement with the abutments l9, and as the elements 1 clear the abutments and are retracted within the yoke as shown in Fig. l, the springs 28 will automatically cause the abut-w ments [9 to return to the position of Fig. 3.

When the elements -1 are in their pressure exerting position, as shown in Figs. 2 and 4, i. e., with the piston l at the end of its right-hand movement and the links 9 substantially vertical, the longitudinal axi Y-Yfof each link passes through the center of its pivot 8, and the rotational axis XX of the engaged abutment I9, see Fig. 5. Therefore, thereis in effect a solid connection between the rigid abutment block 22 and the movable die plate 5. As a result, the development of high molding pressures within Cal - of the screws there is shown diagrammatically in Fig. 1, an injection molding device of a type that can be used most advantageously with the present pressure exerting mechanism. Generally speaking, this device consists of a heater' 30 for receiving heatplasticizable material through the operation of a plunger 3| within a feed cylinder 32. Movement of the plunger 3| to the left by a piston 33, operating within a cylinder 34, causes plasticized material to be injected into the dies D at high pressure through an injection nozzle 35. It is tobe noted that even though the pressure per square inch developed within the material by movement of the piston 33 may be many times the pressure developed with the cylinder l4, the dies cannot separate, with the actuating elements 1 rigidly backed up by the abutments l9, as seated in the blocks 22. l

As previously indicated, the yoke l3, together with the die plate 5, cross head H and cylinder I4, is adjustable as a unit within the frame, so that the distance between the die plates 4 and 5 maybe varied in order to accommodate dies of different thicknesses. To this end, the cross head II is movable on the rods l2 carried by the plate 5 while the yoke 13 is shiftable on the same ways 6 which support the die plate 5. The yoke provides extensions 36, having openings 31 for receiving adjusting screws 38 and a nut 39 in threaded engagement with each screw 38, is mounted on each extension 36, so that turning between the screws and the entire yoke assembly. Each screw 38 is connected to an operating shaft 46 rotatably mounted within an opening 4| passing through an end member 42 of the main frame. The end 'of the shaft 40 carries a worm gear 43, and the shaft together with its screw 38, is locked against axial movement on the frame by a nut 44 and the shoulder 38a between the screw 38 and adapted to drive the shafts 40 in unison to shift the entire yoke assembly with respect to the frame, for the purpose of adjusting the'distance between the die plates, when it is desired to make a change in the thickness of the'dies D. It is to be particularly noted that any such adjustment of the yoke l3 within the frame I in no way affects the setup of the pressure exerting mechanism wherein the cross-head H is movable on the rods l2 independently of the yoke. That is to say, the die'plat 5 is always rigidly backed up .by the engaged elements 1 and yoke abutments it to prevent separation of the dies entirely irrespective of the distance between the abutments and the die plates 4.

We claim:

1. A pressure exerting and locking mechanism, comprising in combination a stationary member, an abutment turnable about an axis fixed with respect to said stationary membena movable pres- 38 will cause relative movement,

aerate? ment on its pivotal axis into wedging relation with said abutment to maintain said movable member in pressure engagement, accompanied by turning of said abutment with respect to said element.

2. A pressure exerting and locking mechanism, comprising in combination a stationary member, an abutment turnable about an axis fixed with respect to said stationary member, a movable pressure exerting member, an operating member movable with respect to said abutment, and a locking element pivotally connected to said movable member and to said operating member about axes parallel to said abutment axis, with movement of said operating member serving to swing said element on its pivotal axis to dispose its free end into wedging relation with said abutment to maintain said movable member in pressure engagement, accompanied by self alinement of said abutment with respect'to the free end of said element as said abutment turns about its axis.

3. A pressure exertingand locking mechanism, comprising in combination a frame, a member movable on said frame, into pressure exerting p0- sition, an operating member movable on said frame, an abutment carried by said frame and turnable on an axis at right angles to the movement of said operating member, a locking element pivotally connected to said pressure exerting member and to said operating member about axes parallel to the abutment axis, and means for imparting movement to said operating member on said frame, to swing said element into wedging relation with said abutment and maintain said pressure exerting member in operative position with respect to said frame, accompanied by self-alignmentof said abutment as the latter turns on its pivotal axis in response to engagement by said locking element.

4. Apressure exerting and locking mechanism, comprising in combination a frame, a member movable on said frame, into pressure exerting position, an operating member movable on said irame, an abutment pivotally mounted on said trams and turnable about an axis at right angles to the movement of said operating member, a locking element pivotally connected to said pressure exerting member and to said operating member about axes parallel to the abutment axis, and means for imparting movement to said operating member on said frame to first cause said element to move in a straight line on said frame as said pressure exerting member approaches its operative position and then to swing said element on its pivotal axis into wedging relation withsaid abutment to maintain said' member in pressure exerting position, with said abutment being tumable on its axis as said engagement occurs.

5. A pressure exerting and locking mechanism, comprising in combination a frame, a yoke supported by said frame, a pressure exerting member movable on said frame with relation to said yoke. an operating member movable on said yoke, an abutment pivotally mounted on said yoke -and turnable about an axis at right angles to the" vmovement of said operating member, a locking element pivotally connected to said pressure exerting member and to said operating member about axes parallel to the abutment axis, and

means for imparting movement to said operating member on said yoke to first cause said element to move in a straight line on said yoke as said pressure exerting member approaches its operative position and then to swing said element/on its pivotal axis into wedging relation with said abutment to maintain said member in pressure exerting position, with said abutment being tumabie on its axis as said engagement occurs, said yoke, together with said pressure exerting member, said operating member, said abutment and said locking element being adjustable, as a unit, on said frame to determine the initial position of said pressure exerting member, prior to movement of said operating member.

' VICTOR E. ROSENLUND.

CLARENCE S. FUZAK. 

